Forging process



J. C. CUMMINGS FORGING PROCESS Filed Nov. 30 1920 Patented Mar. lll,T1924.

UNHTE STATS JOSEPH C. CUMMINGS, 0F DETROIT, MICHIGAN.

FOJRGING PROCESS.

Application filed November 30, 1920. Serial No. 427,276.

To all whom it may concern.

Be it known that I, JosnPH C. CUMMINGS, a citizen of the United States,and resident of Detroit, in the county of l/Vayne and State of Michigan,have invented certain new and useful Improvements in Forging Processes,of which the following is a specification.

My present invention relates to the manufacture of tools and otherarticles from what is known in the art as high-speed steel, this termdefining metal having tungsten, vanadium and chromium or otheringredients having similar properities. The better qualities ofhigh-speed steel may contain up to say, 17% to 19% tungsten; 3 1/2% to l1 4% chromium, 1% to 1 1/2% of vanadium, and say 1/3% to 3/4% of carbon.

The invention is concerned with an improved process having certain broadfeatures in common with that of Patent to James 1. Waters No. 1,345,045,granted June 29, 1920, and is further concerned with the product of suchimproved process. The process may be employed to produce articles of anyshape but has its preferred application to the making of flat articles,that is, to articles having small thickness compared to the facedimensions, and more specifically to disks to be machined into millingcutters and the like.

According to one feature of the invention, the metal of the ingot orcasting is worked down transversely 1n the usual manner into a billet,thereby increasing the tensile strength by the formation of a grain orfiber longitudinally of the billet. The working is, however, carried onto an extent to form a billet of a cross-section materially smaller thanthat of the plan or face area of the articles to be formed, and blanksof appropriate volume severed from the end of the billet are forged tothe shape desired with the grain extending parallel to the face of thearticles to be produced.

I prefer to carry out my process by cutting off a length of billet ofappropriate volume from stock of any gauge preferably materially smallerthan that of the face of the articles to be formed and to forge saidpiece of metal in a mould of the face dimensions of said article byoperation upon surfaces extending parallel to the grain of the metal,that is. upon surfaces that were part of the surface of the billet fromwhich the piece was severed until the said piece is reduced to a blankof the thickness of the article to be made, and of the shape of themould.

In the preferred specific application of my process to the production ofhigh-speed steel disks, I employ billets of a cross-sec tion muchsmaller than the face area of the disks to be made, said billets beingpref erably rectangular or square in cross-section. A piece being cutoff the end of the billet of a volume substantially equal to that of thedisk to be formed, this piece is reduced to a blank of the thickness ofthe disk by a forging operation upon surfaces that were part of thesurface of the billet from which the piece was severed. This operationis preferably completed in a mould having a circular periphery to limitthe spreading of the metal as it is flattened thereby producing the diskdesired.

The execution of my process results in a novel and superior productembraced in the scope of my invention. A characteristic, particularly offiat articles produced by my process, is that the grain of the metal hasnot only been greatly compacted by the forging, but it extends in adirection paral lel to the face of the article, that is, in thedirection of the greatest dimension, rather than through the thickness,with advantages which will appear fully below.

In carrying out the invention, the successive workings are preferablyperformed at substantially the preferred temperatures set forth in thepatent above referred to.

My invention as above noted is applicable to the manufacture of anyarticles from high-speed steel, but I shall specifically describe theprocess of forming a milling cutter, as shown in the accompanyingdrawings, in which Fig. 1 is a perspective view, shown broken ofi, ofthe ingot,

Fig. 2 is an end view thereof,

Fig. 3 is a view similar to Fig. 1 of the billet to which the ingot isworked down,

Fig. 4 is an end view of Fig. 3,

Fig. 5 is a view of the disk to be formed,

Fig. 6 is a view in transverse section of the refashioned disk; and,

Fig. 7 is a plan view indicating the manner in which the refashioneddisk may be sheared or trimmed to form the cutter.

The direction of the grain or fiber of the steel is roughly shown inFigs. 1 and 3.

The ingot'shown in Figs. 1 and 2 is first reduced in cross-section byworking according to the usual method to form a billet of the dimensionsindicated in Figs. 3 and 4, and preferably rectangular in cross-section,as shown, the billet being of considerably smaller cross-section thanthe face area of the disk articles to be made therefrom, and shown inFig. 6. A length of billet P is then sawed ofl' alongthe line AAindicated in Fig. 3, preferably a little greater in mass and volume thanthe disk into which it is to be converted to allow an excess for flashand scale losses. The parallelopipedonal piece P is now subjected to ahot forging operation upon a lateral surface B, O, D or E that is, anoriginal surface of the billet from which the piece was severed, andwhich therefore extends parallel with the grain or fiber of the metal.In this forging operation the metal is reduced in thickness andcorrespondingly increased in face dimension, the corners beingpreferably worked into a generally circular outline somewhat asindicated in Figure 5.

The disk is then refashioned, preferably in a die, to the form shown inFig. 6 and annealed rior to shearing or trimming to the final orm ofcutter shown in Fig. 7.

In working the stock with the grain extending parallel to the face ofthe flat article to be made in the manner set forth, the forgingoperation tends to compact the grain of the stock, that is, it tends tocause the grain to come close together in a manner which will beexemplified hereinafter. This is particularly so where the stock isreduced by forging, as set forth, to the relatively small thickness ofthe articles to be made. By this compacting process, carbides,tungstides and other compounds in the steel are effectively broken upand spread throughout the mass of the blank, thus producingsubstantially uniform distribution and strength. Micrographs of a blankthus produced are substantially identical in appearance, whether takennear the center or near. the periphery of the blank, longitudinally ortransversely thereof.

Where the smallest dimension of the ar: ticle is not produced by directcompacting of the grain or fiber of the metal in the manner described,as, for instance, where the billets are merely rolled to the diameter ofthe disks which are then machined to cutter form, the working does notpenetrate to sufficient depth to effect uniform strength. Micrographstaken transversely near the center of such billets show a much coarserand less uniform grain than near the periphery and micrographs takenlongitudinally of the billet also show a materially coarser grain thanthose taken transversely thereof. This difference in structure increasesproportionally as the size of the billet increases. Gutters produced bythis messes method are, therefore, subject to fracture, and this isparticularly true of cutters of more than three inches in diameter.

Moreover, in the case of a cutter machined from a billet of. the cutterdiameter, the grain extends axially of the cutter or through thethickness thereof. In such cases, it is substantially only the cohesiveforce between the short grain or fibers which resists peeling orbreaking of the teeth, so

finished cutter the grain, therefore, extends substantiallylongitudinally of many of the teeth, whereby the great tensile strengthof the steel fiber comes into play to resist the great stresses againstthe teeth occurring in operation. Thus, the losses of time and money dueto fracture of cutters and to peeling or breaking of teeth aresubstantially eliminated by my invention. It is also found that a keenerand more accurate cutting edge can be maintained where the disk isformed by my method, than where the grain extends through the thicknessthereof.

To further point out the beneficial results to be attained by my method,a specific numerical illustration will be given. Let it be assumed thatdisks 5 1/8 inches in diameter and 3/4 inch in thickness are to be madeaccording to my invention. Starting with an ingot (Fig. 1) say 8 inchessquare or 64 square inches in cross-section, the same would be reducedby preference to square stock (Fig. 3) 2 1/4 inch square or 5.0625square inches. A length of billet P of 3 inches would have a volumeslightly greater than that of the disk to be produced, the excess beingallowance for flash and scale. After this length of billet is forgedinto disk form by my method, as set forth, the largest sectiontransversely of the grain will be a diametrical section through the diskand this area will be 5 1/8x3/4 inches or 3.84 square inches. Themaximum cross-section of the disk in Fig. 5 is, therefore 3.84/64 ofthat of the original ingot, and the cross-section of the ingot has thusbeen worked down and compacted to an area only 6% as great. The metalalong the various sections of the disk parallel to the diametricalsection is obviously compacted to an even greater extent so that theentire length of the grain is effectively compacted.

Lesaeec Where a disk of the same dimensions, that is, 5 1/8 inches indiameter and 3/4 inch in thickness is made by machining methods from around bar of approximately the same diameter as the disk it is necessaryto start with a much larger ingot, say twelve inches square or 144square inches in crosssection; The cross-section of the round 5 1/4 inchbar produced therefrom is 20.629

square inches, or say 14.4% of that of the ingot. The 5 1/8 disk is thencut off and machined Without any further forging, whereas by my methodas above shown the crosssectional area of the ingot was worked down to amaterially greater extent, that is, to 6% of its original area and thenfurther finishforging which is particularly effective at the edges. Thusby my invention, the fibers have been compacted considerably more thantwice as much as by the other method, although I start with a muchsmaller ingot. By this greater compacting of the grain, the product isnot only rendered more uniform, but the tensile strength transversely ofthe grain or the cohesion between the fibers is multiplied.

Hence a cutter produced by my method is far superior to one produced byother methods, firstly, because the metal has been worked to such extentthat there are no weak spots at which fracture can take place, secondly,because the grain extends length wise of a considerable number of theteeth and the great tensile strength of the metal in the direction ofthe grain operates to resist rupture of the teeth, and thirdly,-becausethe grain or fiber has been compacted to such an extent as to greatlyincrease the cohesive strength between the grain or fibers as comparedwith the product resulting from other methods.

To achieve the best results, with high speed steel,-the successiveforging operations are performed substantially at the temperaturesindicated in the Waters patent above referred to, that is, the blank cutfrom billet P is heated to a temperature around .1900 degrees F., or saybetween 1850 degrees and 1950 degrees, for forging to approximatelydesired thinness and circular shape, as indicated in Fig. 5, while therefashioning in the die to the form shown in Fig. 6 would preferably beat a lower temperature, around 1800 degrees F. or say between 17 50degrees and 1850 degrees.

I claim:

1. The process of forming articles from high-speed tungsten steel of theclass de scribed, which process includes working the cross-section ofthe metal of a billet to a thickness substantially that of the articleto be made, and a width no greater than the maximum dimension of saidarticle and exerting pressure substantially at right angles to the faceof said metal of reduced thickness and at right angles to the grain ofsaid metal to produce the finished article.

2. The process of forming articles from high-speed tungsten steel of theclass described, which process includes working the cross-sectional areaof the metal of an ingot to reduce it to a cross-section rectangularinform and smaller than the largest sectional area of the articles to bemade, severing lengths of appropriate volume and fashioning said lengthsinto the articles desired by a forging operation solely upon surfaces ofthe metal extending along the grain thereof.

3. The process of forging high-speed tungsten steel of the classdescribed, which process includes severing from the end of a billet apiece of appropriate volume but of dimensions different from those ofthe finished article, and fashioning said piece to the desired thicknessby operating solely upon surfaces thereof extending in the direction ofthe grain.

4. The process of forming articles from high-speed tungsten steel of theclass described, which process includes severing from the end of abillet, a piece of the appropriate volume, but of dimensions differentfrom those of the finished article and fashioning said piece byperforming a. flattening operation in a mold upon a surface of the piecethat was part of the surface of the billet.

5. The rocess of formingarticles from high-speed tungsten steel of theclass described, which process includes severing from the end of abillet a piece of appropriate volume but of dimensions different fromthose of the' finished article, and flattening said piece in anappropriate mold by operation upon a Surface that was part of thesurface of the billet, to a thickness substantially equal to onedimension of the article and then performing a shaping operation in adie.

6. The rocess of forming fiat articles of substantia ly uniformdimensions from high-speed tungsten steel billets of a crosssectionmaterially smaller than the plan area of said articles, which processconsists in severing from the end of the billet a piece of appropriatevolume, operating in an appropriate mold upon that portion of thesurface of the piece that was part of the surface of the billet, toreduce the thickness thereof to that of the article while the moldlimits the spread of the metal, thereby producing the contour desired.

7. The process of forming disks of substantially uniform dimensions fromhighspeed tungsten steel billets of a rectangular cross-sectionmaterially smaller than the plan area of the disks, which processconsists in severing from the end of the billet a piece of appropriateVolume, forging in an appropriate disk shaped mold at that portion ofthe surface of the piece that was part of the surface of the billet, toreduce the thickness to substantially that of the disk to be formed,while the mold limits the spread of the metal, thereby producing thecontour desired.

8. In a process of forming articles from blanks of high-speed steel, thestep of forging the metal by operation upon surfaces of the blank thatwere part of the surface of the billet from which it is severed, saidoperation being performed at temperatures high enough for malleabilitybut less than 2000 F.

9. llhe process set forth in claim 2, in which the forging operation isperformed aeeaeee at a temperature between 1850 degrees and 1950 degreesF. a 4

10. The rocess set forth in claim 5 in which the attening operation isperformed at a temperature of approximately 1900 F, and in which theshaping operation is performed at a lower temperature.

ture between 1750 degrees and 1850 degrees F.

Signed at Ann Arbor, in the county of Washtenaw and State of Michigan,this 26th day of November, A. D. 1920.

JOSEPH C. CUMMINGS.

